Pneumatic braces of the foregoing type are fully disclosed in my prior U.S. Pat. No. 4,280,489 and prior pending U.S. patent application, Ser. No. 06/694,700, filed Jan. 25, 1985. Commercial embodiments of the pneumatic brace incorporating the inventions disclosed and claimed in my prior patent and application and adapted to be fitted about the lower leg typically comprise an outer shell member in the form of a U-shaped stirrup, inflatable liners or airbags disposed within the stirrup member in coextensive relation to the upstanding sidewalls thereof, and strap fastening means for maintaining the stirrup member sidewalls in engagement with confronting portions of the lower leg whereby each airbag serves as a firm supporting cushion of pressurized air between the irregular contours of the lower leg and the stirrup member sidewalls.
Because this brace construction is capable of stabilizing the ankle against eversion and inversion without restricting dorsiflexion and plantoflexion while being worn inside a conventional shoe, ambulatory functionality and permitted exercises are feasible thereby encouraging more rapid recovery from various injuries to the lower extremity, e.g. ankle sprains, than otherwise would be possible. As a result of these and other important advantages, the commercial embodiments referred to above which are marketed by AIRCAST INCORPORATED, Summit, N.J., have become widely accepted and recognized throughout the medical and orthopedic community. See for example, Ramey, H. and Jakob, R. P., "Functional Treatment of Fresh Fibular Ligament Lesions Using the AIRCAST* Ankle Brace", Swiss Journal of Sports Medicine, 2-31:53-57, June, 1983; Stover, C. N. and York, J. M. "AIRCAST/AIR-STIRRUP* System For Graduated Management of Lower Extremity Injuries", Scientific Exhibit Paper, American Association of Orthopedic Surgeons, San Francisco, 1979; Stover, C. N., "AIR-STIRRUP Management of Ankle Injuries in the Athlete", American Journal of Sports Medicine, 8-5:360-365, 1980; and Hamilton, W. G., "Sprained Ankles in Ballet Dancers", Foot and Ankle, 3-2:99-102, 1982. * AIRCAST is a trademark and AIR-STIRRUP is a registered trademark of AIRCAST INCORPORATED, Summit, N.J.
As disclosed in my prior '489 patent, column 6, lines 16-31, dorsiflexion of the ankle by a wearer of the patented pneumatic brace causes momentary increase in the internal pressure of each airbag. It is believed by at least some of the authors cited above that htis alternating pressure exerts a "milking effect" on edematous tissues during function which in turn, contributes to a more rapid recovery and/or reduction in swelling.
It has also been demonstrated by the JOBST COMPANY, Peoria, Ill., that treatment of lymphedema may be facilitated by the use of a compression stocking worn about the lower leg. The JOBST compression stocking enhances graduated application of pressure to the lower leg, i.e. relatively greater pressure is applied to the ankle region as opposed to that applied along portions of the lower extremity displaced above the ankle.
However, since the JOBST graduated compression stocking is elastic, it fails to provide sufficient pulsating pressure to achieve the desired pumping or milking effect during ambulatory function.
Certain disadvantages also persist with respect to the AIR-STIRRUP pneumatic brace described in my '489 patent. For example, if the bottom-most fastening straps proximal to the ankle are tightened first, the single airbag in each upstanding sidewall may be over compressed in the ankle region possibly resulting in uncomfortable contact between the bony portions of the ankle (i.e. the malleoli) and the outer hard shell of the brace. Further, in the leg brace version of the AIR-STIRRUP brace which has a greater longitudinal extent along the lower leg than does the ankle brace version, the magnitude of pressure pulsation is less because the larger volume of the airbag used in the leg brace vis-a-vis the ankle brace tends to attenuate compression due to dorsiflexion.